1. Field of the Invention
This invention relates to an integrated circuit having a reflector for an acoustic thin film resonator as a portion of the integrated circuit and a method of fabricating the integrated circuit with the reflector and resonator.
2. Brief Description of the Prior Art
High-Q resonators are key components for radio frequency (RF) wireless communication equipment. Resonators are required for filter construction and for production of stable oscillators. A number of materials, such as piezoelectric, high dielectric and surface acoustic wave (SAW) can be used to build high-Q resonators. However, these materials are generally not compatible with silicon semiconductor processing techniques and therefore cannot be integrated into silicon integrated circuit fabrication processes. Recently, several thin film acoustic resonators (TFR) were examined as candidates for integrated resonators as referenced by K M. Lakin et al., "Stacked Crystal Filters Implemented With Thin Films", 43rd Annual Symposium on Frequency Control, (1989) and C. W. Seabury et al., "Thin Film ZnO Based Bulk Acoustic Mode Filters", 1997 IEEE MTT-5 Digest. These designs demonstrated the size advantages and the Q-factor suitable for silicon integration. However, these designs also required additional non-planar processing, such as, for example, a deep silicon etch to create an air gap under the resonator structure or use of a high stack of quarter wave reflectors to isolate the thin film acoustic resonators. Accordingly, these designs are not suitable candidates for use in conjunction with an integrated circuit fabrication process.